Purchasing and other transactions routinely occur over the Internet in electronic marketplaces and other business systems. These electronic systems typically allow buyers to locate suitable sellers and sellers to locate suitable buyers. However, it is often difficult to engage in transactions in the electronic systems while maintaining the anonymity of one or more of the participants. For example, when a transaction involves the supply of goods or services to a purchaser, it is often difficult to hide the identity of the purchaser from the supplier of the goods or services. As particular examples, it may be difficult to balance the need for anonymity against the need to guarantee or carry out payment for the goods or services and the need to assure timely fulfillment of an order.